Mobile communication system and method of information processing for improving user experience in the mobile communication system

ABSTRACT

The present invention relates to a method for processing information between mobile communication systems in order to prevent the degradation of user-experienced performance when different types of mobile communication networks are used. The method for processing information at user equipment (UE) to improve user-experienced performance of a mobile communication system includes performing a data communication through a first network and receiving, from a policy server, a routing policy including a validity condition which is information about a condition of designating a UE status for handover. The method further includes, in the handover, if a searched second network satisfies the validity condition, performing the data communication through the second network. Accordingly, a network for data transmission can be selected using a routing policy created in consideration of a UE status or a network status, thereby enhancing user-experienced performance.

TECHNICAL FIELD

The present invention relates to a method for processing informationreceived or to be transmitted in order to prevent the degradation ofuser-experienced performance during the use of a non-3GPP access networksuch as a wireless LAN in a situation where a 3GPP access networkcoexists with the non-3GPP access network.

BACKGROUND ART

Normally a mobile communication system has been developed so as to offera communication based on user's mobility. With related technologiesadvanced rapidly, a mobile communication system has reached a stage toprovide a high-speed data communication service as well as a voicecommunication.

Recently 3GPP (3rd Generation Partnership Project) has been discussingthe standard of LTE (Long Term Evolution) which is one ofnext-generation mobile communication systems. LTE technology realizes ahigh-speed packet based communication that has a transmission rate up toabout 100 Mbps which is higher a currently available data transmissionrate. Typically discussed for this is an approach to reduce nodesdisposed on channels through a simplified network structure or anapproach to make wireless protocols be maximally close to wirelesschannels.

However, despite such efforts, it is still difficult to satisfyincreasing users' demands by using limited wireless channel resources.Especially, due to the advent of smart phones, user saturation in a datacommunication network becomes more and more higher. In view of suchsituations, mobile communication operators try to solve the saturationof a data network by utilizing a non-3GPP access network, such as awireless LAN, WiFi, or IEEE 802.11 family, which allows a user'swireless access through the ISM (Industrial Scientific Medical) band.Namely, a part of user's traffic is transmitted using a non-3GPP accessnetwork, e.g., an AP (Access Point) of a wireless LAN, rather than to a3GPP access network through a base station. In this case, an operatorcan cope effectively with a rapid increase in data by using a frequencyband of a non-3GPP access network as well as a frequency band of a 3GPPaccess network.

In order to offer a policy for selectively using a 3GPP access network,i.e., LTE, and a non-3GPP access network to UE, 3GPP defines ANDSF(Access Network Discovery and Selection Function). This will bedescribed hereinafter with reference to FIG. 1.

FIG. 1 is a schematic diagram illustrating a typical network structureusing UE and ADNSF.

Referring to FIG. 1, ANDSF communicates with UE through the S14interface operating on the IP (Internet Protocol) layer and offers apolicy associated with a selection of 3GPP and non-3GPP access networksto UE. Both UE and ANDSF employ the S14 interface on the IP layer inorder to send or receive data formed of MO (Management Object) of OMA DM(Open Mobile Alliance Device Management). The IP layer connectionbetween UE and ANDSF is offered by a 3GPP or non-3GPP access network.Additionally, to communicate with ANDSF, UE should create a securetunnel first of all by using a separate security method. Suchrequirements may cause an increase in time required to offer a policyfrom ANDSF to UE. This means that a policy of ANDSF is not sufficient toconsider dynamically changed status of UE or access network.

DISCLOSURE OF INVENTION Technical Problem

FIG. 2 is a diagram illustrating a general operation of a typicalnetwork using a policy of ANDSF.

Referring to FIG. 2, UE receives data by using an access network 1 atoperation 200. Then, at operation 202, ANDSF creates a routing policyassociated with a selection of 3GPP and non-3GPP access networks andtransfers it to the UE. The routing policy is Policy (in case of ISMP)or ISRP. This routing policy includes an update policy, routing criteriaincluding location, time and APN, or the like. In case the routingpolicy is Policy, location only may be included instead of the routingcriteria.

When handover is performed at operation 204, the UE performs a searchfor a specific network to be accessed on the basis of the receivedrouting policy. Next, at operation 206, the UE receives data by using anaccess network 2. If handover is required again, the UE searches foranother network on the basis of the received routing policy at operation208 and performs access to a selected network.

The routing policy includes a field of the update policy and a field ofthe routing criteria as well as criteria about indicating which accessnetwork will be selected by the UE. The update policy indicates, using aone-bit flag, whether a request for update is allowed or not in case apolicy received from the ANDSF is not suitable for the UE to use. Todetermine whether to update a policy by means of one-bit may cause theUE to fail to request an update in spite of a need of a policy update,or unnecessarily invite excessively frequent updates of a policy.

Meanwhile, the routing criteria include a user's location, time and APN(Access Point Name) to which a policy will be applied. The UE determineswhether to apply a policy received from an operator according to therouting criteria. However, a combination of a user's location, time andAPN has a limitation in fully reflecting the status of the UE and accessnetwork. For example, in case of complying with a current architectureof the ANDSF, the UE may fail to consider a congestion level of awireless LAN network at the time of access to the wireless LAN networkand, in this case, user-experienced performance may be extremelydeteriorated.

Solution to Problem

In order to solve the above problems, the present invention provides amethod for processing information at user equipment (UE) to improveuser-experienced performance of a mobile communication system, themethod comprising performing a data communication through a firstnetwork and receiving, from a policy server, a routing policy includinga validity condition which is information about a condition ofdesignating a UE status for handover; and in the handover, if a searchedsecond network satisfies the validity condition, performing the datacommunication through the second network.

Additionally, in order to solve the above problems, the presentinvention provides a method for processing information at a policyserver to improve user-experienced performance of a mobile communicationsystem, the method comprising creating a routing policy including avalidity condition which is information about a condition of designatinga UE status for handover and then transmitting the routing policy to UE(User Equipment).

Advantageous Effects of Invention

According to the present invention, the UE considers the status thereofor the status of an access network when determining whether to transmittraffic by using a wireless LAN, thus improving user-experiencedperformance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating a typical network structureusing UE and ADNSF.

FIG. 2 is a diagram illustrating a general operation of a typicalnetwork using a policy of ANDSF.

FIG. 3 is a diagram illustrating a method for transferring a routingpolicy between mobile communication systems in accordance with the firstembodiment of the present invention.

FIG. 4 is a diagram illustrating a method for transferring a routingpolicy between mobile communication systems in accordance with thesecond embodiment of the present invention.

FIG. 5 is a diagram illustrating a method for transferring a routingpolicy between mobile communication systems in case a policy serveroperates on an IP layer in accordance with an embodiment of the presentinvention.

FIG. 6 is a diagram illustrating a method for transferring a routingpolicy between mobile communication systems in case a policy serverinterworks with MME in accordance with an embodiment of the presentinvention.

MODE FOR THE INVENTION

In the following description, well known functions or configurations maynot be described or illustrated in detail to avoid obscuring the essenceof the present invention. Hereinafter, embodiments of the presentinvention will be described more fully with reference to theaccompanying drawings.

Although the following description of embodiments of the presentinvention will be focused on a general 3GPP (3rd Generation PartnershipProject) system and a wireless LAN (i.e., IEEE 802.11 family), thesubject matter of the present invention may be substantially applied toany other communication/computer system having similar technicalbackground and system configuration as will be understood by thoseskilled in the art. Further, although the following description ofembodiments of the present invention will consider ANDSF (Access NetworkDiscovery Service Function) or a policy server as an entity having anindependent function, this may be located as being physically embodiedtogether with any other entity within the communication system. Also,even though the description of the present invention will be based onthe form of 3GPP Rel-10 ANDSF MO, various kinds of control informationand associated operations proposed by this invention may be applied,with a slight variation, to any other case based on any different formof control information.

The ANDSF is the 3GPP standard for offering technology about handoverbetween different communication networks. The ANDSF collects and storesin advance information about each network and information aboutoperator's policy, and offers such information to UE at the request ofthe UE. Since the ANDSF can offer operator policy information associatedwith handover, it is referred to as a policy server.

In order to solve problems that may occur due to the application of apolicy in connection with the selection of an access network, thepresent invention proposes a method for allowing the policy server toconsider the status of a user and the status of an access network. Forthis, the first proposed scheme is to extend routing criteria containedin a routing policy (Policy or ISRP) transferred to UE by the policyserver such that the extended routing criteria can include a validitycondition (i.e., user status condition information). If the routingpolicy transferred to UE is Policy, the validity condition may bedirectly included in the Policy rather than being included in therouting criteria. The following description of the present inventionwill be focused on a case in which the routing policy is ISRP and thusthe validity condition is included in the routing criteria. However, thesubject matter of this invention may be applied to other case in whichthe routing policy is Policy and further the validity condition isdirectly included in the Policy.

The validity condition is information about conditions of designating UEstatus for handover and is information offered to UE by the policyserver. The validity condition may include a combination of a UEmobility level, a UE battery life, a congestion level, and the like.When such conditions are satisfied, UE may perform handover by applyinga policy. For example, only if the congestion level of a wireless LANwhich can be used by UE is equal to or less than a specific congestionlevel specified in the routing policy, the UE may actually use thewireless LAN.

Additionally, the present invention proposes a scheme to extend anupdate policy expressed as a one-bit flag such that the extended updatepolicy can include the validity condition. The validity condition in theupdate policy is necessary condition information for requesting theupdate policy and offered to UE by a policy server. Also, the validitycondition in the update policy is composed of one or a combination of atleast two of information about signal strength between UE and an accessnetwork, information about a UE starvation level, information about aconnection attempt failure level, information about a UE battery life,and the like. When these conditions are satisfied, UE may request anupdate policy from the policy server.

Additionally, the present invention proposes a scheme to interwork thepolicy server with eNB (enhance Node B, also known as evolved Node B) inorder to solve a problem caused by the operation of the policy serversuch as ANDSF on the IP layer and further in order to determine a policyin consideration of the status of a 3GPP access network.

Additionally, the present invention proposes a scheme to interwork thepolicy server with MME in order to reduce the number of interfacesrequired for directly interworking the policy server with eNB andfurther in order to consider the status of a core network as well as a3GPP access network.

FIG. 3 is a diagram illustrating a method for transferring a routingpolicy between mobile communication systems in accordance with the firstembodiment of the present invention. Namely, FIG. 3 shows a scheme inwhich extended routing criteria include a validity condition (i.e., userstatus condition information). The validity condition refers toconditions offered to UE (User Equipment) by a policy server, includinga combination of information about a UE mobility level, a UE batterylife, a congestion level, and the like. When these conditions aresatisfied, the UE may perform handover by applying a policy.

At operation 300, the UE performs an IP communication by using the firstnetwork, i.e., an access network 1, connected thereto. At operation 302,the policy server creates a routing policy according to an operatorpolicy and transfers it to the UE. Here, since a process of connectingthe UE and the policy server is a well known function, a descriptionthereof will be skipped. According to the present invention, a validitycondition (i.e., user status condition information) is newly containedin routing criteria. This validity condition is composed of one or acombination of at least two of information about a UE battery life,information about a UE mobility level, and information about acongestion level of an access network measured by the UE. Such conditioninformation is defined as a threshold concept, and the UE may apply arouting policy for selecting an access network only if a measured valuesatisfies a given condition.

Next, at operation 304 for handover, the UE performs a search for anaccess network contained in given policy criteria. Then the UE checks avalidity condition contained in routing criteria. If an access network 2which is the second network satisfies a given validity condition, the UEperforms a data communication by using the access network 2 at operation306 and from then on. For example, if the congestion level (e.g., around trip time of packet, a congestion window size, a STA number, autilization level, etc.) of the wireless LAN access network 2 measuredby the UE is equal to or less than a congestion level contained in thevalidity condition, the UE transmits and receives data through access tothe wireless LAN access network 2.

Additionally, at operation 308, the UE checks the status of the secondnetwork by continuously checking the validity condition contained in therouting criteria. If the validity condition is not satisfied, the UEchanges an access network. Alternatively, if the validity condition isnot satisfied, the UE requests a policy update from the policy server.

In FIG. 3, the UE receives the policy criteria during a datacommunication with a specific access network and, at the time ofhandover, determines whether a target network satisfies the validitycondition. If the target network satisfies the validity condition, theUE may perform a data communication through a connection with the targetnetwork.

FIG. 4 is a diagram illustrating a method for transferring a routingpolicy between mobile communication systems in accordance with thesecond embodiment of the present invention. Specifically, FIG. 4 shows ascheme in which an update policy which has been expressed as a one-bitflag in a routing policy is extended so as to include a validitycondition (i.e., user status condition information) according to thesecond embodiment. The validity condition contained in the update policyrefers to conditions offered to UE by a policy server and is composed ofone or a combination of at least two of information about signalstrength between the UE and an access network, information about a UEstarvation level, information about an attempt failure level,information about a UE battery life, and the like. When these conditionsare satisfied, the UE may request a new update policy from a policyserver.

Referring to FIG. 4, the policy server offers a routing policy to the UEat operation 400. At this operation, the routing policy includes routingcriteria and an update policy. And the update policy contains a validitycondition (i.e., user status condition information). The validitycondition may be composed of one or a combination of at least two ofinformation about signal strength between the UE and an access network,information about a UE battery life, information about a UE mobilitylevel, information about a UE starvation level, information about anattempt failure level, and the like. This validity condition is athreshold concept, and the UE may send a request for an update policy tothe policy server if a measured value satisfies a given validitycondition.

At operation 402, the UE performs a data communication with an accessnetwork through a 3GPP/non-3GPP connection. Then, at operation 404, theUE checks a validity condition contained in the update policy receivedfrom the policy server at operation 400. If a current UE status or cellstatus satisfies the validity condition, the UE transmits a request foran update policy to the policy server at operation 406. At this time,the UE transfers a reason for request and information about a current UEstatus, together with a request for an update policy. The reason forrequest may be one of extreme starvation, an attempt failure, a low UEbattery life, and the like. The current UE status indicates an actualstatus of the UE, including a starvation level, an attempt failurelevel, a residual quantity of UE battery, and the like.

Then, at operation 408, the policy server stores therein informationcontained in the update policy request received from the UE. Further,the policy server updates a new routing policy by checking the status ofthe UE and an access network through the information from the UE. Next,at operation 410, the policy server transfers the updated routing policyto the UE.

FIG. 5 is a diagram illustrating a method for transferring a routingpolicy between mobile communication systems in case a policy serveroperates on an IP layer in accordance with an embodiment of the presentinvention. Specifically, FIG. 5 shows a scheme in which the policyserver such as ANDSF operates on the IP layer and thereby is interworkedwith eNB (enhance Node B, also known as evolved Node B) such that arouting policy can be determined in consideration of the status of a3GPP access network. The eNB is a node that can continuously check thestatus of UE in a connected mode and also directly check the status ofthe 3GPP access network.

Referring to FIG. 5, at operation 500, the UE accesses the eNB andperforms a data communication using the 3GPP access network. Atoperation 502, the eNB checks the status of a cell or the status of theUE. The cell status includes information about a cell location, acongestion level, or the like, and the UE status includes informationabout a UE location or the like.

If the cell status or the UE status needs handover, namely, if non-3GPPaccess is determined to remove UE traffic, the eNB requests at operation504 the policy server to create a routing policy for moving the UE to anon-3GPP access network. This request for the creation of the routingpolicy may include information about the UE or 3GPP access network inorder for the policy server to create the routing policy according tothe UE status, and may further include information about QoS relatedmatters of the UE.

At operation 506, the policy server stores therein such information,received from the eNB, about the UE or 3GPP access network and QoSrelated matters of the UE. Additionally, the policy server determines arouting policy in consideration of the stored information. As discussedabove in FIGS. 3 and 4, this routing policy may include the extension ofrouting criteria and update policy.

At operation 508, the policy server transfers the created routing policyto the eNB. Then, at operation 510, the eNB transfers the routingpolicy, received from the policy server, to the UE. At this operation,the eNB transfers the routing policy by using RRC message of the 3GPPaccess network. The RRC message has a security based on a securityscheme between the UE and the eNB and allows a considerable reduction ina delay time because of packet transmission on the layer 2 level.

At operation 512, the UE performs a search for a non-3GPP access networkfor handover and determines whether the searched access networksatisfies the routing criteria. If the access network satisfies therouting criteria, the UE performs at operation 514 a data communicationby using the non-3GPP access network.

Meanwhile, using SIB (System Information Block) which is informationbroadcasted through a broadcast channel, the eNB may notify whether anynon-3GPP access network accessible by the UEs exists within its owncoverage. For example, if there is any accessible wireless LAN in thecoverage of the eNB, the eNB transmits the “LAN exists” flag marked with“Yes” through SIB. Then the UEs can recognize in advance whether ausable wireless LAN exists or not. If the above flag is marked with“No”, the UE may skip an unnecessary channel search since there is nousable wireless LAN. Alternatively, the eNB may insert the type of anon-3GPP access network, which is usable in the coverage, into the SIB.For example, if indexes indicating WLAN and WiMAX are contained in aneighbor non-3GPP access network list of the SIB, the UE can recognizein advance that usable WLAN and WiMAX exist nearby.

FIG. 6 is a diagram illustrating a method for transferring a routingpolicy between mobile communication systems in case a policy serverinterworks with MME in accordance with an embodiment of the presentinvention. Specifically, FIG. 6 shows a scheme in which the policyserver is interworked with MME (Mobility Management Entity) such thatthe number of interfaces required for directly interworking the policyserver such as ANDSF with the eNB can be reduced and also the status ofa core network as well as a 3GPP access network can be considered. TheMME stores the status of the UE which is in an idle mode as well as in aconnected mode.

Referring to FIG. 6, at operation 600, the UE accesses the eNB andperforms a data communication using the 3GPP access network. Atoperation 602, the eNB requests the policy server to create a routingpolicy for moving the UE to a non-3GPP access network, depending on acell status or a UE status. The cell status may include informationabout a cell location, a congestion level, or the like, and the UEstatus may include information about a UE location or the like. Thisoperation 602 is an additional step and thus may be skipped.

At operation 604, the MME determines to move the UE to the non-3GPPaccess network on the basis of the UE status or cell status checkedautonomously or information received from the eNB. Then, at operation606, the MME requests the policy server to create a routing policy. Thisrequest for the creation of the routing policy may include informationabout the cell status or UE status such that the policy server cancollect information about the UE or 3GPP access network and reflect iton the creation of the routing policy, and may further include QoSrelated matters of the UE.

At operation 608, the policy server stores therein such informationabout the cell status or UE status received from the MME, and thendetermines a routing policy in consideration of the stored information.As discussed above in FIGS. 3 and 4, this routing policy may include theextension of routing criteria and update policy.

At operation 610, the policy server transfers the created routing policyto the MME. Then, at operation 612, the MME transfers the routingpolicy, received from the policy server, to the UE. At this operation,the MME transfers the routing policy by using NAS message. The NASmessage has a security based on a security scheme between the UE and theMME.

Next, at operation 614, the UE performs a search for a non-3GPP accessnetwork and determines whether the routing criteria are satisfied. Ifthe searched access network satisfies the routing criteria, the UEperforms at operation 616 a data communication by using the non-3GPPaccess network.

In brief, a method proposed by this invention in order to improveuser-experienced performance when the UE performs handover, is asfollows.

A mobile communication system is composed of UE (User Equipment), apolicy server, and a network accessed by the UE to transmit and receivedata. In the mobile communication system, the policy server may beformed as an independent element or alternatively as being interworkedwith eNB or MME.

According to the present invention, the policy server checks a currentUE status and cell status and then creates a validity condition (i.e.,user status condition information). The validity condition refers toconditions of designating the UE status for performing handover orinformation about necessary conditions of requesting an update policy.The validity condition is contained in routing criteria constituting therouting policy or in the update policy.

While transmitting or receiving data through a network, the UE checks,through routing criteria received from the policy server, the validitycondition which is condition information for designating the UE statusfor performing handover. In such handover, if the status of a searchednetwork satisfies the validity condition, the UE performs a seamlessdata communication after handover to the network.

Alternatively, the policy server transfers, to the UE, a routing policyincluding information about necessary conditions of requesting an updatepolicy. If a current UE status satisfies the validity condition, the UErequests the update policy from the policy server. At this time, the UEtransfers information about a current UE status and cell status togetherwith the request for the update policy. Then the policy server creates arouting policy by referring to information about the received UE statusand cell status. And the policy server transfers the created routingpolicy to the UE.

As discussed hereinbefore, the routing policy is created at the policyserver in consideration of a current UE status or network status, and ifthe routing policy is satisfied, the UE performs handover or requests anupdate policy. Therefore, user-experienced performance can be enhanced.

While the present invention has been particularly shown and describedwith reference to an exemplary embodiment thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of thisinvention as defined by the appended claims.

The invention claimed is:
 1. A method for performing a handover by aterminal, the method comprising: receiving wi-fi offloading informationincluding a wireless local access network (WLAN) access threshold from abase station of a first network; identifying a signal received from asecond network corresponding to a WLAN; comparing a signal strength ofthe received signal with the WLAN access threshold included in the wi-fioffloading information; and receiving a data packet from the secondnetwork when the signal strength of the second network is equal to orgreater than the WLAN access threshold.
 2. The method of claim 1,wherein the wi-fi offloading information is received via a radioresource control (RRC) message.
 3. The method of claim 1, wherein thewi-fi offloading information is received via a system information block(SIB).
 4. The method of claim 1, wherein the wi-fi offloadinginformation is transmitted from an access network discovery andselection function (ANDSF) to the base station.
 5. A terminal forperforming a handover, the terminal comprising: a transceiver configuredto receive wi-fi offloading information including a wireless localaccess network (WLAN) access threshold from a base station of a firstnetwork; and a controller configured to: identify a signal received froma second network corresponding to a WLAN, compare a signal strength ofthe received signal with the WLAN access threshold included in the wi-fioffloading information, compare a signal strength of the received signalwith the WLAN access threshold included in the wi-fi offloadinginformation, and receive a data packet from the second network when thesignal strength of the second network is equal to or greater than theWLAN access threshold.
 6. The terminal of claim 5, wherein the wi-fioffloading information is received via a radio resource control (RRC)message.
 7. The terminal of claim 5, wherein the wi-fi offloadinginformation is received via a system information block (SIB).
 8. Theterminal of claim 5, wherein the wi-fi offloading information istransmitted from an access network discovery and selection function(ANDSF) to the base station.
 9. A method for performing a handover by abase station of a first network, the method comprising: receiving wi-fioffloading information including a wireless local access network (WLAN)access threshold from an access network discovery and selection function(ANDSF); and transmitting the wi-fi offloading information including theWLAN access threshold to a terminal, wherein a signal received from asecond network corresponding to a WLAN is identified by the terminal,wherein a signal strength of the received signal is compared with theWLAN access threshold included in the wi-fi offloading information bythe terminal, and wherein a data packet is received from the secondnetwork when the signal strength of the second network is equal to orgreater than the WLAN access threshold.
 10. The method of claim 9,wherein the wi-fi offloading information is transmitted via a radioresource control (RRC) message.
 11. The method of claim 9, wherein thewi-fi offloading information is transmitted via a system informationblock (SIB).
 12. A base station for performing a handover, the basestation comprising: a transceiver configured to: receive wi-fioffloading information including a wireless local access network (WLAN)access threshold from an access network discovery and selection function(ANDSF), and transmit the wi-fi offloading information including theWLAN access threshold to a terminal; and a controller configured tocontrol the transceiver, wherein a signal received from a second networkcorresponding to a WLAN is identified by the terminal, wherein a signalstrength of the received signal is compared with the WLAN accessthreshold included in the wi-fi offloading information by the terminal,and wherein a data packet is received from the second network when thesignal strength of the second network is equal to or greater than theWLAN access threshold.
 13. The base station of claim 12, wherein thecontroller is further configured to control the transceiver to transmitthe wi-fi offloading information via a radio resource control (RRC)message.
 14. The base station of claim 12, wherein the controller isfurther configured to control the transceiver to transmit the wi-fioffloading information via a system information block (SIB).